test.swift

import UIKit
import AVFoundation


class ViewController: UIViewController {
    
    // Session
    var myFrontSession : AVCaptureSession!
    var myBackSession : AVCaptureSession!
    
    var myFrontVideoLayer: AVCaptureVideoPreviewLayer!
    var myBackVideoLayer: AVCaptureVideoPreviewLayer!

    // device Front Camera & Back Camera
    var myFrontDevice : AVCaptureDevice!
    var myBackDevice : AVCaptureDevice!

    // output of the image
    var myFrontImageOutput : AVCaptureStillImageOutput!
    var myBackImageOutput : AVCaptureStillImageOutput!
    
    var pickerController = UIImagePickerController()
    var appDelegate = UIApplication.sharedApplication().delegate as! AppDelegate

    @IBOutlet weak var frontView: UIView!
    //@IBOutlet weak var backView: UIView!
    @IBOutlet weak var backImgView: UIImageView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // create session
        myFrontSession = AVCaptureSession()
        myBackSession = AVCaptureSession()

        
        // get the list of devices
        let devices = AVCaptureDevice.devices()
        
        // store back camera in myDevice
        for device in devices{
            /*
            case Unspecified
            case Back
            case Front
            */
            if(device.position == AVCaptureDevicePosition.Front){
                //myDevice = device as! AVCaptureDevice
                myFrontDevice = device as! AVCaptureDevice
            }
            
            if(device.position == AVCaptureDevicePosition.Back){
                //myDevice = device as! AVCaptureDevice
                myBackDevice = device as! AVCaptureDevice
            }
        }
        print(myFrontDevice)
        print(myBackDevice)
        
        startFrontCamera()
        startBackCamera()
        
    }
    
    func startFrontCamera() {
        print(myFrontDevice)
        do {
            let videoFrontInput = try AVCaptureDeviceInput(device: myFrontDevice)
            // add above to session
            myFrontSession.addInput(videoFrontInput)
            myFrontImageOutput = AVCaptureStillImageOutput()
            myFrontSession.addOutput(myFrontImageOutput)
        } catch let error as NSError {
            // Handle any errors
            print(error)
        }
        
        // create layer to display image
        myFrontVideoLayer = AVCaptureVideoPreviewLayer(session: myFrontSession)
        myFrontVideoLayer.videoGravity = AVLayerVideoGravityResizeAspectFill
        //myFrontVideoLayer.frame = self.view.bounds
        myFrontVideoLayer.frame = frontView.bounds
        
        // add view
        frontView.layer.addSublayer(myFrontVideoLayer)
        myFrontSession.startRunning()
        
    }
    
    func startBackCamera() {
        print(myBackDevice)
        do {
            //let myDevice = AVCaptureDevice.defaultDeviceWithMediaType(AVMediaTypeVideo)
            let videoBackInput = try AVCaptureDeviceInput(device: myBackDevice)
            // add above to session
            myBackSession.addInput(videoBackInput)
            myBackImageOutput = AVCaptureStillImageOutput()
            myBackSession.addOutput(myBackImageOutput)
        } catch let error as NSError {
            // Handle any errors
            print(error)
        }
        
        myBackVideoLayer = AVCaptureVideoPreviewLayer(session: myBackSession)
        myBackVideoLayer.videoGravity = AVLayerVideoGravityResizeAspectFill
        //myBackVideoLayer.frame = self.view.bounds
        myBackVideoLayer.frame = backImgView.bounds
        
        
        // add view
        backImgView.layer.addSublayer(myBackVideoLayer)
        myBackSession.startRunning()
        
        
    }
    
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }


}